1. Field of the Invention
The present invention, in general, relates to a system for use with an internal combustion engine at oil well and natural gas well sites and, more particularly, to apparatus to provide a warning and to shut down the operation of an internal combustion engine when a concentration of methane gas is detected that is exceeding a preset level.
Oil wells and natural gas wells require the use of equipment that is powered by internal combustion engines. The equipment is used, for example, to pump well contents to the surface and to operate mobile diagnostic equipment that is periodically inserted into existing wells.
A problem sometimes encountered at oil and/or natural gas well sites is that a hydrocarbon, often in the form of methane gas, is either pumped from or otherwise expelled naturally from such well sites.
Furthermore, it is not possible to accurately predict when a significant quantity of methane gas may be expelled from an oil or gas well into the atmosphere. A rupture of piping may contribute to the release of methane gas, as would normal fluctuations in the substances that are encountered within each well being pumped or tested.
The danger that arises from the release of volatile vapors into the atmosphere occurs when the ambient concentration of hydrocarbons, such as are found in methane gas, increase beyond a safe level. In that event, an internal combustion engine will experience an acceleration, known as engine "run-away".
This occurs because an internal combustion engine reacts to an increased source of energy derived from burning methane gas present in the air. Usually, a concentration level in excess of one percent methane produces the danger of a "run-away" event occurring.
A "run-away" condition also causes the engine to increase its internal operating temperature significantly and may result in the engine expelling glowing particulates from the exhaust stack into the atmosphere. These glowing particulates may ignite the hydrocarbons in the atmosphere immediately outside the engine exhaust stack, resulting in damage or injury.
Accordingly, there exists today a need for a methane monitor and engine shutdown system for use at oil well and natural gas well sites to warn of a possible engine run-away condition.
2. Description of Prior Art
Devices are known that will detect combustible gas at various places. For example, U.S. Pat. No. 2,219,391 to Jacobsen, that issued Oct. 29, 1940, describes an apparatus for automatically indicating and controlling the concentration of a combustible gas or vapor between certain limits, or approaching the lower explosive limit.
U.S. Pat. No. 2,573,390 to Blanchard, that issued Oct. 30, 1951, describes an apparatus for detecting the presence of a gas in drilling mud.
U.S. Pat. No. 3,838,597 to Montgomery et al, that issued Oct. 1, 1974, describes a method and apparatus for monitoring the operation of a pump used in withdrawing fluids from a well by differentiation of an electrical load signals.
U.S. Pat. No. 4,118,148 to Allen, that issued Oct. 3, 1978, describes a system for control of a downhole pump by the displacement of the fluids and gas discharged by the pump.
U.S. Pat. No. 4,507,053 to Frizzell, that issued Mar. 26, 1985, describes an apparatus for shutting down a pump when a pump off condition, such as the detection of an inadequate flow is observed.
U.S. Pat. No. 4,508,488 to Pikna, that issued Apr. 2, 1985, describes apparatus to control the pumping of fluids from a well to optimize flow rates.
U.S. Pat. No. 4,788,529 to Lin, that issued Nov. 29, 1988, describes a gas flow regulator with alarm and control features to close a gas supply when a condition arises.
U.S. Pat. No. 4,859,151 to Reed, that issued Aug. 22, 1989, describes a control device to regulate a pump when the flow rate is less than a predetermined amount.
While the structural arrangements of these devices, at first appearance, have similarities with the present invention, they differ in material respects. These differences, which will be described in more detail hereinafter, are essential for the effective use of the invention and which admit of the advantages that are not available with the prior devices.